For the topping, heat the butter in a large skillet over medium heat; add the onion and cook until softened but not browned, about 5 to 7 minutes, stirring occasionally. Add the thyme, salt, black pepper, and garlic, and cook 1 minute, stirring constantly. Add the breadcrumbs and cook until light golden brown, about 5 minutes, stirring occasionally. Turn off heat and stir in the parsley; set aside for now.
For the casserole, heat the butter and oil in a large skillet over medium-high heat; add the turkey bacon and cook until crispy, about 3 minutes, stirring occasionally. Turn heat down to medium and add the onion, carrot, celery, and bell pepper; cook until starting to soften, about 5 minutes, stirring occasionally. Stir in the garlic, thyme, oregano, salt, black pepper, and bay leaf and cook 1 minute, stirring constantly. Stir in the flour and cook 1 minute.
Add the stock, tomato paste, and beans and bring to a boil; turn heat down and simmer (uncovered) until the veggies